"Telegram received. Stop at Cairo. Submarine boat Tracer ordered there to take you and Cobb through Central Sea. "By order Secretary State. "HARRY G. COLLINS, _Chief Clerk_." Cobb read it through twice ere he ventured any remark; then, handing it back while a troubled look overspread his countenance, he said: "Cairo is in Illinois, at the junction of the Ohio with the Mississippi; but I fail to comprehend the import of the words 'Central Sea.' The submarine boat spoken of does not surprise me, for I would naturally expect that that which was almost an accomplished fact in 1887, would be an actual success at this late date." "There is no Ohio River, or not as was in your time. The Ohio is now but a small stream flowing into the Central Sea," replied Rawolle. "Again those words 'Central Sea;' what does it mean? Is there an inland sea?" and Cobb looked inquiringly at both of the others. "There is," slowly spoke Rawolle. "And a mighty big one, too," put in Lyman. Cobb was highly educated and of a sanguine temperament; he neither doubted what seemed impossible, nor did he believe until the facts were clearly before his mind. He was perfectly cognizant of the physical geography of the United States, and did not understand under what conditions a great inland sea could have been formed, or maintained. [Illustration] Settling himself back in his seat and breaking the circuit of the electric light to lessen the glare in their faces, Rawolle continued: "I will give you some facts concerning this sea, for, now that you are one of a new generation, you have much to learn, and we cannot pass the hours between now and bed-time to better advantage. On the last day of August, 1916," he began, "at about 14 dial, or as they then said, 2 P. M., that which was taken, at the time, as the shock of a great earthquake, was felt by thousands of persons throughout the central portion of the United States. In less than two hours later, the nation was informed of the true nature of the shocks which followed each other in rapid succession. It was the explosion of natural gases deep down in the strata of the earth's crust, and the scene of the disturbances covered a vast area of territory. During the following week the shaking and trembling of the earth caused great destruction in many cities and towns not otherwise affected. Houses fell, the water supply failed, and other serious results were experienced. But throughout portions of the area now covered by the Central Sea, the scene was terrible, awe-inspiring, horrible. The earth heaved and sank; huge cracks opened, and flames hundreds of feet high shot into the air; thunder and lightning added to the horrors of the situation. The bursting of the earth's crust was attended by an appalling roar and crash, as if a million peals of thunder had combined in one grand effort to terrify mankind; then came a pall of dense, black smoke that wrapped the land in darkness.